Thermostat switch



Sept. 30, 1930. v. o. BEAM THERMOSTAT SWITCH Filed Dec. 5, 1928 INVENTOR V0 BL /ZN BY 4 I ATTUR' EY Patented Sept. 30, 1930 UNITED STATES PATENT OFFICE VILYNN O. BEAM, 0! TOLEDO, OHIO, ASSIGNOB TO THE SURFACE COMBUSTION (10., INCORPORATED, OF TOLEDO, OHIO, A. CORPORATION OF NEW YORK THERMOSTAT SWITCH Application filed December a, 1928. Serial m'szasos.

This invention relates to improvements in thermostat switches adapted to make and break an electrical circuit.

It is an object of the invention to provide a circuit breaker and closer which shall be of a very sensitive character and which on a relatively short movement of the operating mechanism such as a thermostat will impart a relatively long movement to the movable switch member.

Another object of the invention is to provide a device of the character indicated which shall be simple in its construction, positive in its operation, and which can be produced at low cost.

Other objects of the invention will appear as the apparatus is described in detail.

In the drawings, Fig. 1 is an elevation of an ignition pilot apparatus showing my inventionembodied therein, arts being in section; and Fig. 2 is an enlarged perspective view of the switch element itself.

10 indicates a rectangular frame at the bottom of which are secured two binding osts 12 and 14 each of which carries an ad ustable contact point 12 and14'. Openings 16 in the frame opposite the contact points permit a tool such as a screw driver to be inserted through the side limbs of the frame for adusting the contact oints as may be required.

ltlovable between the contact points 12 and 1418is a switch element generally indicated at Fixedly secured at the upper end of the frame and projecting therefrom is a tube 22 having at its outer end a burner head 24 which serves as an ignition pilot for a main burner 26. Fixedly secured to the tube 22 below the burner head 24' is a bracket 28 adapted for serves to ignite the main burner 26 as will now be readily understood.

The tube 22 intermediate its ends is provided with a side opening 34 through which some of the gaseous mixture may pass for burning outside of the tube to heat it. A shield 36 disposed alongside the tube in front of the opening 34 tends to confine the flame lengthwise of the tube so as to more effectually heat the tube. When the gas is burning at the head 24, the flame will be propagated down to the gas issuing through the side opening 34 as will be readily understood. The tube 22 is preferably made of brass since this material has a relatively high coefficient of expansion.

Secured to the bracket28 in spaced relation to the tube 22 is a steel rod 40 which at its other end is slidably supported in an opening in the frame 10. Electrically insulated from but fixedly secured in any suitable manner to the free end of' the rod 40 is a relatively thin and flat metallic strip 42 which forms part of the switch element 18. Electrically insulated from the frame and supported thereby is a binding post 44 which serves as an anchorage for asecond thin and flat metallic strip 46. These strips are -prefer ably formed by doubling a ribbon-like stri on itself. A rivet 48 may be passed throug the strips to form a contact element. The switch element 18 may therefore be said to comprise a head, through which the rivet 48 passes, with thin flexible branches formed by the strips 42 and 46.

The mode of operation of the device is sub stantially as follows: \Vhen the thermal tube 22 is heated it expands longitudinally and the steel rod 40 is carried with it with the result that the latter moves relatively to the frame 10. Since the blade 42 is secured to the end of therod 40 and forms in effect a prolongation thereof, itsterminal, whichmay be considered as being the same as the rivet 48, tends to move towardthe binding post 44. The blade 46, however, offers 0 position to such movement but eventually ws away from the blade 42 and in so doin causes the terminal rivet 48 to move toward the fixed contact 12, it being understood that the blade 42 also flexes at a point or line near its point of anchorage to the rod 40. When the thermal tube 22 cools, the movement of the rod 40 is reversed and eventually a point i, is reached where both blades straighten out with the result that contact 48 moves away from fixed contact 12. Continued reverse (downward) movement of the blade 42 is opposed by the blade 46. However, as the movement continues blade 42 will bow away from the blade 46 with the result that contact 48 moves towards contact 14, it being understood that blade 46 also flexes at a point or line near its anchorage 44.

15 From the foregoing description it will be readily appreciated that a relatively short longitudinal movement of the rod 40 imparts a relatively great lateral movement to the movable element 18.

The blades 42 and 46 need not be of special spring material; material such as ordinary sheet brass is well adapted for the purpose and such material is preferred. lVhile it is preferred to form the blades by bending a ribbon-like strip upon itself, nevertheless individual short strips may be employed to make up the element 18.

It is not necessary to successful operationof the device that the distance from the blade anchorage 44 to the fixed point of joinder of the blades be equal to the distance from said anchorage to the contact point 14 or 12'. A point of joinder somewhere intermediate such distance suffices provided it be not too close to the anchorage 44. If such point is too close to the anchorage 44 the stresses set up during the operation of the device may be severe enough to loosen the stressed parts. Where the point of joinder is at an interme- 40 diate point only one of the blades need be of a length to reach the contacts 12' and 14 as will be readily understood.

It will, of course, be understood'that the binding posts 12, 14 and 44 are in circuit 45 with a controlling element as for example a motor operable to open and close a gas cutoff valve for the burner 26. While I have shown two fixed contacts 12 and 14 it will be understood that one ofthem may be omitted without in any manner interfering with the operation of the switch element.

What is, claimed is: 1. The combination, with a thermostat "having a circuit contact and a means movable with respect thereto when the thermostat ,is

heated, of a movable switch element comprising a pair of thin strips arranged in facing relation, an anchorage to which one end of one of the strips is secured, the adjacent end on of the other strip being secured to said means,

the strips at a point remote from said anchorage being fixedly connected together to form a floating terminal, said contact being positioned in the path of movement of said terminal.

2. The combination, with a thermostat having a circuit contact and a rod longitudinally movable with respect to said contact when the thermostat is heated, of a movable switch element comprising a pair of thin strips arranged in facing relation, an anchorage to which one end of one of said strips is secured, the adjacent end of the other strip being secured to said rod, the strips at a point remote from said "anchorage being connected together to form a floating terminal, said contact being positioned in the path of movement of said terminal.

3. The combination, with a circuit contact and a member movable with respect thereto, of a switch element having a head with two branches of ribbon-like form, an anchorage to which the terminal of one of the branches is secured, the other branch terminal being connected to said member, and said contact being arranged laterally of the head of said element.

4. The combination, with a circuit contact and a member movable with respect thereto, of a switch element comprising a metallic ribbon doubled upon itself one terminal of the ribbon being secured to said member, an anchorage to which the other terminal is secured, the doubled end of the ribbon being arranged to engage said contact.

5. The combination, with a circuit contact and a rod movable longitudinally with respect thereto, of a metallic ribbon doubled upon itself, both leaves thereof being disposed in substantial alinement with said rod, the free end of one leaf being fixedly connected to the adjacent end of the rod, and an anchorage to which the end of the other leaf is fixedly secured, said contact being disposed adjacent the doubled end of the ribbon in the path of lateral movement thereof.

6. The combination, with a circuit contact and a member movable with respect thereto, of a switch element having a head with two branches which are of ribbon-like form, the ends of the branches being secured the one to said member and the other to an anchorage adjacent thereto, said contact being arranged laterally of the head of said element.

7. The combination, with a thermostat having a circuit contact and a means movable with respect thereto when the thermostat is heated, of a movable switch element having two branches which are of ribbon-like form with their wide sides in opposition, the ends of the branches being secured the one to said means and the other to an anchorage adjacent thereto. 8. In combination, a tube adapted to be heated by flames resulting from the burning of gas issuing from the tube, a bracket for suspending the tube from a burner, a frame supported by the tube, a rod secured at one end to the bracket and slidably supported at its other end in said frame, a circuit conlln 

